a) Field of the Invention
An automatic handling machine for microtitration plates is to be understood in the broadest sense as meaning an arrangement of various devices and appliances which are connected to one another via a transport arrangement, by means of which the microtitration plates are supplied to the individual devices and appliances (referred to below as work stations) in an order which is determined by the preset process sequence.
b) Description of the Related Art
In addition to the microtitration plates, it is necessary, for example, to move vessels for cultures, nutrient media, buffers, reagents, dissolved substances and washing liquids. The devices and appliances may, for example, be: washing devices, metering devices, stackers, suction devices, microtitration plate stores with optional access (so-called hotels), incubators (with heating and/or cooling), measurement devices (photometers, luminometers, units for measuring fluorescence, nephelometers), cooling and heating devices (e.g. thermocyclers), mixers, magnetic-particle handling devices.
At various workstations, e.g. the metering device, the corresponding operation can be performed without the microtitration plate having to be taken off the transport arrangement. At other workstations, e.g. an incubator or a stacking device, it is necessary to remove the microtitration plate from the transport arrangement.
An automatic handling machine with a transport arrangement in which a carriage can be moved to and fro in a straight line, on two parallel rails of a carriage guide, between two limit positions is known in practice. The individual workstations are arranged on or above the transport arrangement, in a sequence corresponding to that of the process. On the carriage, there are advantageously a plurality of places of deposit, on which the microtitration plates are deposited next to one another in a defined order. The defined order of depositing may, for example, be achieved by means of a centering pin arrangement on each of the places of deposit, which describes the periphery of the microtitration plate.
At the workstations at which it is necessary to remove the microtitration plate from the transport device, a lifting device is arranged under the carriage guide. This lifting device engages, by means of four bolts which are guided parallel to one another, between the rails, through openings which are provided for this purpose in the carriage, on the bottom of the microtitration plate and lifts the latter off the place of deposit. The four bolts are arranged in such a manner with respect to one another and with respect to the microtitration plate resting on the carriage that the surface center of gravity of the microtitration plate lies in the quadrilateral which the four bolts form. In the lifted position, the microtitration plate can be removed, for example by a gripper or a loading arm.
By way of example, there are incubators in which the microtitration plates are automatically conveyed into the inner chamber and out of this chamber by means of a loading arm which belongs to the incubator and is similar to a cake-slice. On the loading arm, there may be centering elements which prevent the microtitration plate from slipping on the loading arm when the latter is moved.
To allow the microtitration plate to be deposited on and picked up from a bearing surface in the interior of the incubator, there has to be a cutout, into which the loading arm fits, in the plane of the bearing surface. If the microtitration plate is picked up from and deposited on the carriage directly, a corresponding cutout has to be provided in the carriage as well. The transfer between the transport device and the loading arm is easier if, as described above, the microtitration plate is lifted off the carriage by means of a lifting device. The loading arm is then narrower than the distance between the bolts and only has to be moveable in a single plane.
Many measurement appliances have an appliance carriage which can be displaced in two coordinates and is able to move the microtitration plate within the fixed measurement -beam path, so that all the cavities in the microtitration plate can be measured.
The transfer between the transport arrangement and the appliance carriage may either be carried out by a gripper picking up the microtitration plate from the carriage and depositing it on the appliance carriage or vice versa, or by the microtitration plate being lifted in the manner described and the appliance carriage, which in this case is designed as a frame which is open on one side, moving in under the lifted microtitration plate, which is then deposited as the lifting device is lowered.
For complex tasks to be performed by the automatic handling machines, the linear arrangement of the workstations on the transport arrangement results in arrangements of appliances which take up very large amounts of space. If a plurality of microtitration plates are transported simultaneously on the carriage in the automatic handling machine, the workstations have to be arranged in succession in accordance with the process sequence. For example, there may be a need for a plurality of rinsing devices if the xe2x80x9crinsingxe2x80x9d step has to be repeated a number of times in the process sequence. Although in this case the process sequences for a plurality of microtitration plates may partially overlap in time, the common transport means that the step which lasts the longest is the determining factor for the total operating time.
By contrast, if there is only one microtitration plate in the automatic handling machine, although it is possible to approach workstations a number of times by means of transport in two directions, the total operating time becomes even slower, since the process sequences for the individual microtitration plates always have to take place one after the other in terms of time.
A further disadvantage is that changes in the process sequence result in unnecessarily long transport paths, since the workstations are then no longer approached in the order in which they are arranged.
The invention is based on the object of providing, taking into account the known transport arrangement and lifting device, a novel arrangement for transporting microtitration plates which makes it possible to move a plurality of microtitration plates independently of one another and overlapping one another in terms of time and which allows a flexible operating regime with short transport paths.
The transfer of the microtitration plates within the transport device and between the transport device and various transport means, such as the loading arm of an appliance or an appliance carriage, is to be achievable using simple sequences of movements.
According to the invention, this object is achieved, for an arrangement for transporting microtitration plates, in an automatic handling machine comprising at least one linear-transport device on which a carriage, which has at least one place of deposit for a microtitration plate, is transported in a straight line, under automatic control, between two limit positions. A lifting device is included with vertically displaceable bolts by which the microtitration plates can be lifted off or deposited on the carriage. At least one rotary device is also included in which a rotary element which has at least one resting place for a microtitration plate can be moved, under automatic control, about a fixed rotation shaft. The rotary device is designed and arranged in such a way with respect to the linear-transport device that the resting place can be rotated between the place of deposit and the microtitration plate which has been lifted and is resting on the bolts, so that the surface centers of gravity of the place of deposit of the resting place and of the microtitration plate lie on a line which is parallel to the bolts.
According to the invention, the arrangement for transporting microtitration plates comprises a linear-transport device 1 and at least one rotary device 2. The arrangement of the individual workstations with respect to one another and with respect to the transport arrangement fixes the length of the transport path between the individual workstations. Workstations which during the process sequence have to be approached selectively or even a number of times by the same microtitration plate are advantageously distributed around a rotary device 2. The rotary device 2 may also serve to connect a plurality of linear-transport devices 1. Also, rotary devices 2 may be arranged on both sides of the linear-transport device 1. Appliances which in the process sequence are always approached in succession by a microtitration plate are advantageously arranged next to one another, in this order, along a linear- transport device 1. The rotary device 2 and the linear-transport device 1 can be controlled independently of one another, so that at least two microtitration plates can independently approach workstations at the same time.
The invention is to be explained below with reference to the drawings.